Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/64—Polyesters containing both carboxylic ester groups and carbonate groups

Definitions

• This invention relates to the modification of polyethylene terephthalate with a small amount of a polycarbonic acid ester of 4,4-dihydroXydiphenyl-2,Z-propane.
• the invention is concerned with the formation of a novel high molecular weight polycondensate of diethylene glycol terephthalate and, as a modifying agent, a high molecular weight polycarbonic acid ester of 4,4- dihydroxydiphenyl-2,2-propane.
• co-polycondensates have been made from ethylene glycol and terephthalic acid together with other acids, such as isophthalicacid or the mono-sodium sulfonic acid salt of -sulfo-isophthalic acid.
• One object of the present invention is to provide a process for the preparation of a modified polyethylene terephthalate whereby the resulting modified. polyester will exhibit an improved affinity for dyestuffs without losing the desirable properties of the unmodified. polyester.
• Another object of the invention is to provide a novel polyester product which has an improved appearance and abetter melt stability by comparisonwith the unmodified polyethylene terephthalate.
• Still another object of the invention is to provide a modified polyethylene terephthalate which is equally useful for the production of articles by injection molding as well as for the spinning of fibrous or filamentary products.
• the polycarbonic acid ester can be added to the diethylene glycol terephthalate monomer at the beginning of or durand should have a mean molecular weight of at least about 15,000 up to about 80,000. Those polycarbonic acid esters having a mean molecular weight of 50,000 to 70,000 are especially suitable for the purposes of the present invention.
• the polycarbonic acid ester can be added to the condensation reaction medium in powdered or granulated form and rapidly dissolved so as to be readily dispersed in the reaction medium by mechanical agitation. The preparation of 4,4'-dihydroxydiphenyl- 2,2-propane and its subsequent conversion into the polycarbonic acid ester are described in detail by H.
• modified polyester of this invention is the monomeric diethylene glycol 'terephthalate normally used in the pro-
• polycondensate of the invention should usually contain at least about by weight of this monomer in condensed form.
• the preferred modified polyesters of this invention are those which consist essentially of the di- -ethylene glycol terephthalate component polycondensed with the polycarbonic acid ester component, and such preferred polyester products should normally contain not. more than'5% by weight," and preferably less than 1%.
• dyestuffs and fillers or the like can be sub; sequently added without changing or substantially modifying the essential and desirablecharacteristics of the new polyester.
• dyestuffs and fillers or the like can be sub; sequently added without changing or substantially modifying the essential and desirablecharacteristics of the new polyester.
• These and other minor alterati ons can be made in the polyester composition without departing from the spirit and scope of the present invention.
• the diethylene glycol terephthalate component of the invention is most easily obtained by the usual ester interchange of dimethyl terephthalate with ethylene glycol in the presence of a conventional transesterification catalyst.
• the transesterification product in which the diethylene glycol terephthalate can already be partly condensed, may be used directly with the addition of the polycarbonic acid ester modifying agent, and the reaction mixture then subjected to polycondensation according to conventional batch or continuous polymerization methods.
• the polycondensation reaction is normally carried out at temperatures up to about 300 C., preferably about 280 C., under a high vacuum and/or in the presence of an inert gas. Also, the polycondensation is carried out for a period of time sufficient to give a linear polyester having a mean molecular weight of at least about 9,500.
• the polyester product of this invention is to be commercially employed in the form of textile filaments or fibers, it is generally desirable to obtain a product having a molecular weight of about 10,000 to 25,000, and where the end product is to be used in the manufacture of molded articles without being stretched or oriented, it is generally desirable to obtain a molecular weight of about 25,000 to 30,000.
• fiber-forming polyester is used herein with reference to a linear polyester having a sufiiciently high molecular weight to be spun and stretched into an oriented fiber or filament.
• Suitable catalysts for the ester interchange reaction and the subsequent polycondensation reaction include the familiar metal, metal oxide or metal salt catalysts such as zinc acetate and antimony trioxide.
• the amount of catalyst and the period of time for the condensation reaction can be varied over a relatively broad range, and the final molecular weight of the polyester product can be easily determined by measurement of the melt viscosity.
• the modified linear polyesters obtained according to the polycondensation process of the present invention are distinguished in part by the fact that their softening point is only slightly lower than the unmodified polyethylene terephthalate.
• a polyethylene glycol terephthalate modified with by weight of the polycarbonic acid ester modifying agent softens or melts at a temperature of only about 45 C. lower than does the pure polyethylene glycol terephthalate.
• molded articles or textile products such as filaments and fibers produced from the modified polyesters of the invention are completely unyellowed and actually exhibit a brightness which is not obtained with the corresponding products of the unmodified polyester.
• the fibrous products of the invention also show good crease-resistance in both the dry state and the moist state, and these fibrous products are highly stable to chemical agents which tend to cause saponification.
• the modified fiber-forming polyesters of the invention are especially useful in textile materials because they can be very deeply dyed with dispersion dyestuffs, preferably by the so-called carrier dyeing method in which the fiber is dyed in the presence of a swelling agent in the form of a suitable organic solvent.
• the dyeing properties of the modified polyesters are quite excellent even with a relatively small addition of about 3 to 6% by weight of the polycarbonic acid ester.
• any of the methods commonly employed for dyeing polyesters can be used with the fibrous modified polyester products of the present invention, and no special techniques are required because the modified polyesters have a stability against saponification which is equal to the stability of the unmodified polyethylene terephthalate.
• the addition of the polycarbonic acid ester modifying agent also causes a considerable improvement in the thermal stability of the polyester product.
• the polyester decomposes quite rapidly after it has been melted, and the decomposition reaction causes not only a severe reduction in the degree of polymerization, i.e., a reduction of the molecular weight as measured by the melt viscosity, but also produces decomposition products which remain in the polymer and make it quite difficult to extrude or otherwise mold and work the final product.
• the modified polyesters according to the present invention have a much improved melt stability.
• unmodified polyethylene terephthalate undergoes a viscosity reduction of 25-27% when maintained at 280 C. for a period of 30 minutes
• the modified polyethylene terephthalate containing 5% by weight of the polycarbonic acid ester as obtained by the present invention undergoes a viscosity reduction of only 12% when heated at the same temperature and for the same period of time.
• This melt stability of the new polyester is especially advantageous in the injection molding of shaped articles.
• the addition of the polycarbonic acid ester modifying agent retards the crystallization speed of the polyethylene terephthalate, thereby facilitating the extrusion or injection molding of the polyester and also improving the mold stability of the shaped products.
• Example 1 50 kg. of dimethyl terephthalate were transesterified with 44.5 kg. of ethylene glycol in the presence of 0.015% by weight of zinc acetate and 0.02% by weight of anti mony ltrioxide in an autoclave equipped with an agitator and a distillation column. The reaction components were heated to C., and in the course of the next 2 hours the temperature of the reaction was raised to 200 C. and the liberated methanol distilled off. By further raising the temperature to 230 C., 14 liters of glycol were then removed by distillation. 3 kg.
• the solid polyester After being broken up into particles, the solid polyester was in a form suitable for the production of extruded or spun products from a melt.
• the modified polyester had a solution viscosity of 1.50 (measured as a 1% solution in m-cresol at 20 C.) and a melting point of 258.5 C. It was possible to produce filaments from this polyester by the conventional melt spinning process, and these filaments were dyed very deeply with the dispersion dyestufi Palanil Blue R in the presence of an organic swelling agent as a carrier.
• Example 2 100. kg. of dimethyl terephthalate were transesteri fied with 89 kg. of ethylene glycol in the presence of 0.015% by weight of zinc acetate and 0.0 2% by weight of antimony trioxide.
• the reactants were heated to 160 C. and the temperature. was then raised *within 2 hours to 200 C. while distilling off the liberated methanol. A further temperature elevation to 230 C. brought about the distillation of 28 liters of glycol.
• the resulting polycondensation product had a solution viscosity of 1.65-
• the polycarbonic acid ester modifying agent of the present invention permits an improvement in the dyeability of the polyester without any substantial reduction in such properties as resistance to saponi-fication, crease-resistance, high melt viscosity and the like.
• the modified polyester of the present invention exhibits an unusual improvement in the melt stability and a slower crystallization in the molded product. All of these factors contribute to a highly improved polyester in the form of a modified polyethylene terephthalate, and this improvement is achieved without departing from conventional techniques in the reaction conditions and apparatus required for production and use of the polyester product.
• a process for the production of a modified high molecular weight fiber-forming polyester which comprises: co-polyc-ondensing diethylene glycol terephthalate with about 0.5 to 6% by weight of a polycarbonic acid ester of 4,4'-dihydroxydiphenyl-2,2-propane, said polycarbonic acid ester having a mean molecular weight of at least about 15,000 up to about 80,000.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Polyesters Or Polycarbonates (AREA)

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Cited By (8)

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Citations (4)

• 0
  • BE BE627483D patent/BE627483A/xx unknown
  • NL NL289302D patent/NL289302A/xx unknown
• 1962
  • 1962-03-09 DE DE19621545138 patent/DE1545138A1/de active Pending
• 1963
  • 1963-01-21 AT AT46763A patent/AT252572B/de active
  • 1963-01-25 CH CH95363A patent/CH410413A/de unknown
  • 1963-02-14 GB GB6097/63A patent/GB964485A/en not_active Expired
  • 1963-03-08 US US263728A patent/US3313862A/en not_active Expired - Lifetime

Patent Citations (4)

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